Attributes (Cooling Tower Selector) - Johnson Controls - Metasys - LIT-12011147 - Software Application - Controller Configuration Tool - 15.0

Controller Tool Help

Brand
Johnson Controls
Metasys
Product name
Controller Configuration Tool
Document type
User Guide
Document number
LIT-12011147
Version
15.0
Revision date
2022-11-18
Language
English

The following table describes the attributes used by the Cooling Tower Selector modules:

Table 1. Cooling Tower Selector Attributes

Name

Type 1

Description

Default Value

Available Capacity

V

Provides the sum of the capacities of the enabled towers.

0

Display units come from Flow Units.

Current Capacity

G, V

Provides the sum of the capacities of the devices currently on (that is, Device nn Status = On).

0

Display units come from Flow Units.

Current Efficiency

V

Indicates the capacity weighted efficiency of the devices currently commanded to On.

0

Display Units: %

Current/Power Units

 

Indicates the units used for the current/power. These units are not currently used.

A

Set Name: Unit

CW Commanded Flow

 

Indicates the capacity of the active condenser water pumps. The Pump Selector provides this value, if used. The Cooling Tower Selector uses the maximum of Process Variable and CW Commanded Flow to determine when to start and stop the cooling towers.

0

Display units come from Flow Units.

Minimum Value: 0

Device Info

 

Provides a structure of arrays containing individual information of each device. This structure contains: Rated Capacity, Rated Current/Power, and Peak Efficiency.

 

Device nn Capacity

 

Indicates the flow capacity of each device in selectable units (where nn is 01-08).

 

Device nn Cmd

V

Provides the request commands to each cooling tower (where nn is 01-08).

False

Device nn Enable

 

Indicates the Disable/Enable state of the devices (where nn is 01-08).

True

Device nn Runtime

 

Indicates the runtimes of the devices (where nn is 01-08).

0

Display Units: Hours

Device nn Start Count

 

Indicates the number of starts performed by each device (where nn is 01-08).

0

Device nn Status

 

Indicates the current Off/On state of the devices as reported by the hardware itself (where nn is 01-08). These inputs are used to enforce the Minimum On and Minimum Off times.

Off

Set Name: Off/On

Flow Units

 

Indicates the units used for the flow depending on the Units of the application.

l/s, gpm

Set Name: Unit

Interstage Off Delay

 

Delay after an Off command before starting to downstage again.

15

Display Units: Min

Range: 0.1-120

Interstage On Delay

 

Delay after an On command before starting to upstage again.

15

Display Units: Min

Range: 0.1-120

Iso Valve nn Cmd

V

Provides the request commands to each cooling tower isolation valve (where nn is 01-08).

False

Iso Valve Stroke Time

 

Indicates the amount of time that the Cooling Tower Selector waits from the time the it opens the isolation valve to the time it commands the tower fan on.

25

Display Units: Sec

Range: 0-120

Low Load

 

Indicates the only operating chiller has been commanded off to provide chilled water more efficiently.

False

Min Off Time

 

Indicates the minimum amount of off time applied to all cooling towers.

1

Display Units: Min

Range: 0-60

Min On Time

 

Indicates the minimum amount of on time applied to all cooling towers.

1

Display Units: Min

Range: 0-60

Peak Efficiency

 

Indicates the peak efficiency of each cooling tower. The Cooling Tower Selector chooses the devices with the highest value first.

85

Display Units: %

Range: 50-100

Predicted Adjusted Efficiency

SC, V

Indicates the Predicted Efficiency of the Required Devices (steady state device commands) adjusted for runtime imbalances, start count imbalances, start/stop differences, and start/stop efficiency penalties.

0

Display Units: %

Predicted Efficiency

SC, V

Indicates the expected efficiency based on the Required Devices.

0

Display Units: %

Process Variable

 

Provides the required tower flow from the Chiller Selector.

0

Display units come from Flow Units.

Rated Capacity

 

Indicates the cooling capacities of each device.

0.1

Display units come from Flow Units.

Rated Current/Power

 

Indicates the rated current of each device.

0

Display units come from Current/Power Units.

Required Devices

SC, V

Provides an integer output representing the packed bits of the desired steady state set of towers commanded On.

For example, a value of 88 means: 0-1-0-1-1-0-0-0 which indicates device 4, 5, and 7 are On, and the rest are Off.

0

Required Interim Devices

SC, V

Provides an integer output representing the packed bits of the intermediate devices requested to turn on while the Cooling Tower Selector moves toward the desired steady state.

0

Rotate Now

 

Causes an immediate re-evaluation of the required devices to provide the required capacity to meet the current required flow based on the current Device Runtime or Start Counts or both.

False

Rotation Mode

 

Determines how rotation is processed:

  • 0: None. The module does not attempt to equalize either runtimes or start counts of the individual devices.
  • 1: Run Time. The module attempts to equalize the runtimes of the individual devices.
  • 2: Start Counts. The module attempts to equalize the start counts of the individual devices.
  • 3: Both. The module attempts to equalize both start counts and run times of the individual devices.

None

Set Name: Rotation Mode

Sequence Row

  Indicates the sequence table row number that the module attempts to move toward while following device timers and statuses. This input is available when the Sequence Row Control input is True. If the input value is out of range or if a sequence table is not present, Sequence Row input is ignored.

0

Sequence Row Control

  Enables Sequence Row parameter to enable devices. False

Sequence Row Transition Delay

  When Sequence Row becomes False, this indicates the amount of time the selector does not make any staging decisions.
Note: This time is ignored when System Enabled becomes False.

Default: 0.2 minutes

Minimum: 0.1 minutes

System Enabled

 

Disables/enables the Cooling Tower Selector. When System Enabled is False, the Cooling Tower Selector downstages to zero capacity.

Note: When False, the isolation valves to the towers are closed.

False

Total Current/Power

V

Indicates the total actual current/power output of all currently operating devices.

0

Display units come from Current/Power Units.

1 C - Configuration Mode Only, G - Default Element (Generated State, if applicable), SC - Simulation and Commissioning Modes Only, V - Calculated Value (Outputs)